1. Field of the Invention
This invention relates generally to fuel cell reformers, and, more particularly, to identifying an activation of a burst disk relating to a fuel cell system.
2. Description of the Related Art
Fuel cells are showing significant promise for replacing conventional sources of power in a variety of contexts, including cars, buses, houses, commercial buildings, and the like. The three main arguments in favor of fuel cells are abundance, efficiency, and cleanliness. First, the primary fuel for fuel cells is hydrogen, which is the most abundant element in the universe. Second, the efficiency of a fuel cell may exceed the Carnot Cycle limit while operating at a relatively low temperature. For example, a fuel cell operating at 80° C. is typically two to three times as efficient as an internal combustion engine, which may also require substantially higher operating temperatures. Third, the by-products of fuel cell operations are typically benign. For example, water is the only by-product of a fuel cell powered entirely by hydrogen.
One common type of fuel cells is a polymer electrolyte membrane (PEM) fuel cell. This type of fuel cell may also be referred to as a proton exchange membrane fuel cell, a solid polymer electrolyte (SPE) fuel cell, or a polymer electrolyte fuel cell. In operation, hydrogen and oxygen are introduced into an anode and a cathode, respectively, of the PEM fuel cell. The hydrogen dissociates into electrons and protons, and the protons diffuse through an electrolyte membrane, such as a Nafion™ membrane produced by DuPont, that separates the anode from the cathode. When the protons reach the cathode, they react with the oxygen to form water and heat. The electrical current created by the movement of the protons generates a voltage difference of approximately 0.7 volts between the anode and the cathode.
There are, however, a number of drawbacks to using pure hydrogen as the primary fuel for a fuel cell. Hydrogen gas has a relatively low energy density and there is as yet no significant infrastructure for distributing the hydrogen gas. Although the energy density may be increased by liquefying the hydrogen, the process of liquefaction also adds to the overall cost of the hydrogen fuel. Furthermore, liquid hydrogen must be maintained at a low temperature and is therefore substantially more expensive to distribute than hydrogen gas. Thus, a number of alternative primary fuels have been proposed, including gasoline, methanol, ethanol, naphtha, and the like.
Thus, many types of fuels can be used, some of them hybrids with fossil fuels, but the ideal fuel is hydrogen. If the fuel is, for instance, hydrogen, then the combustion is very clean and, as a practical matter, only the water is left after the dissipation and/or consumption of the heat and the consumption of the electricity. Most readily available fuels (e.g., natural gas, propane and gasoline) and even the less common ones (e.g., methanol and ethanol) include hydrogen in their molecular structure. Some fuel cell implementations therefore employ a “fuel processor” that processes a particular fuel to produce a relatively pure hydrogen stream used to fuel the fuel cell. When using a primary fuel other than pure hydrogen, a reformer, also referred to as a fuel processor, is typically used to produce hydrogen from the alternative primary fuel. Three conventional reformer designs are steam reformers, partial oxidation reformers, and auto-thermal reformers. Steam reformers combine the alternative primary fuel with steam and heat to produce hydrogen. The heat required to operate the system is obtained by burning the alternative primary fuel or excess hydrogen from an outlet of the fuel cell. Partial oxidation reformers combine the alternative primary fuel with oxygen to produce hydrogen and carbon monoxide. The carbon monoxide then reacts with steam to produce more hydrogen. Partial oxidation releases heat, which may be captured and used elsewhere in the system. Auto-thermal reformers combine the alternative primary fuel with both steam and oxygen so that the reaction is in heat balance.
Within the reformers a pressure excursion can occur. In an attempt to prevent damage to the hardware connected to a reactor, know as the balance of plant and the reactor vessel itself, a pressure relief device known as a burst disk is employed to relieve pressure in the event of an excursion. Such a bust disk may contain a switch and electronic hardware to provide an indication of a rupture in the burst disk due to excessive pressure.
Generally, computing resources of a control system associated with the fuel system described above are to be utilized to constantly evaluate the status of these burst disks. State-of-the-art burst disks feature intelligent, complex hardware and I/O allocation in the control hardware to monitor the status of the hardware. This may utilize an resources that could otherwise be used for other operations in the system. Furthermore, additional equipment, such as hardware electronics are required for monitoring the operation of a burst disk This may increase the cost of employing such pressure relief features and/or affect the efficiency of the operation of the system.
The present invention is directed to overcoming, or at least reducing, the effects of, one or more of the problems set forth above.